Photo credit: © Ted van den Bergh/Flickr
Red Swamp Crayfish
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Species at a Glance
The red swamp crayfish, also known as the red swamp crawfish, Louisiana crawfish, or mudbug, is a large and aggressive crayfish whose native range extends from northern Mexico to Florida and north to southern Illinois and Ohio. Often used in classrooms and as a popular food item, this highly adaptable crayfish has escaped to invade the Mid-Atlantic region and beyond, impacting aquatic ecosystems by chewing up vegetation, outcompeting native species, and altering water quality.
Adult red swamp crayfish are a dark red color with raised bright red, white, or black spots (tubercles) covering the body and claws. Juveniles are a uniform gray sometimes overlain with dark wavy lines. Occasionally, a genetic mutation may turn the body and/or claws blue. A distinctive characteristic of this species is that the areola is linear to obliterate. The pincers are narrow and long and the rostrum has lateral spines or notches near its tip. Size is typically 5-13 cm (2-5 in).
The red swamp crayfish most closely resembles the white river crayfish (Procambarus acutus acutus), and the southern white river crayfish (Procambarus zonangulus). White river crayfish have an areola that is narrow, but never obliterated, and the juveniles typically have spots on the carapace instead of wavy lines. White river crayfish can also be found in streams and ditches with a stronger flow than what’s preferred by the red swamp crayfish.
The red swamp crayfish is tolerant of a wide range of habitats, including low oxygen levels, extreme temperatures, pollution, and areas with large water level fluctuations. It prefers marshes, swamps, ponds, and slow-moving rivers and streams where there is plenty of organic debris like logs, sticks, or water-soaked leaves. In times of drought or cold, the red swamp crayfish can burrow into the sediment until conditions are more favorable.
Because this species is widely available through the seafood industry and aquarium trade, it is most likely spread when it is intentionally or unintentionally released. Aquarists who keep them as pets, teachers and students who use them as live study specimens, and consumers who purchased them from live food markets often release this species into the wild. The red swamp crayfish is also able to crawl out of water for long distances at night and during wet weather.
Native to the Gulf Coast and the Mississippi River drainage up to Illinois, the red swamp crayfish has spread widely throughout the United States, and is found in all Mid-Atlantic states.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
The red swamp crayfish can quickly dominate lakes, ponds, rivers and wetlands. It feeds heavily on plants, snails, fish, and amphibians, competing with native crayfish and other species for food and habitat. It can also carry crayfish fungus plague which can lead to declines in native crayfish. In addition, its burrowing behavior can be problematic to levees, dams, and irrigation systems
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).